[Android] RadioButton 點選按鈕

RadioGroup rg1;

RadioButton rb1;

rg1=(RadioGroup)findViewById(R.id.rg1);

rb1=(RadioButton)findViewById(R.id.rb1);

示範

XML

xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <RadioGroup
        android:id="@+id/rg1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <RadioButton
            android:id="@+id/rb1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <RadioButton
            android:id="@+id/rb2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />

        <RadioButton
            android:id="@+id/rb3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    RadioGroup>

    <TextView
        android:id="@+id/t1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/rg1" />
android.support.constraint.ConstraintLayout>

JAVA

public class MainActivity extends AppCompatActivity implements RadioGroup.OnCheckedChangeListener {
    RadioGroup rg1;
    RadioButton rb1,rb2,rb3;
    TextView t1;
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        t1=(TextView)findViewById(R.id.t1);
        rg1=(RadioGroup)findViewById(R.id.rg1);

        rb1=(RadioButton)findViewById(R.id.rb1);
        rb2=(RadioButton)findViewById(R.id.rb2);
        rb3=(RadioButton)findViewById(R.id.rb3);
        rb1.setText("R1");
        rb2.setText("R2");
        rb3.setText("R3");
        rg1.setOnCheckedChangeListener(this);
    }



    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {


        switch (checkedId){
            case R.id.rb1:
                t1.setText("R1");
                break;
            case R.id.rb2:
                t1.setText("R2");
                break;
            case R.id.rb3:
                t1.setText("R3");
                break;
        }


    }
}

展示